Apparatus for atomizing fuel in open-hearth furnaces



Feb. 26, 1952 J. HARTNEY APPARATUS FOR ATOMIZIN? FUEL IN OPENHEARTHFURNACES s Sheets-Sheet 1 Filed Aug. 31, 1948 Feb. 2 6, 1952 J. HARTNEYAPPARATUS FoR ATOMIZING FUEL IN- OPENHEARTH FURNACES s Sheets-Sheet 2Filed Aug. 31, 1948 la weidar 415 fliar/zeg.

m 00 0 .7 0o 1 0 0 ow MOOG TOOL OOOW WOOO MWoOH UMQQ 0 am i Feb, 26,1952 J. L. HARTNEY APPARATUS FOR ATOMIZING F UEL IN OPENHEARTH FURNACESFiled Aug. 51, 1948 5 Sheets-Sheet 5 1'4/ 455 Z- finer/v0? MMMV Ill/1Patented Feb. 26, 1952 APPARATUS FOR ATOMIZING FUEL IN OPEN-HEART HFURNACES James L. Hartney, Chicago, Ill., assignor to United StatesSteel. Company, a corporation of- New Jersey Application August 31,1948, Serial No. 47,034

1 Claim.

This invention relates to improved apparatus for atomizing fuel in openhearth furnaces.

An object of the invention is to provide heat exchangers of improvedconstruction for heating compressed air by heat derived from wasteproducts of combustion.

In accomplishing this and other objects of the invention, I haveprovided improved details of structure, a preferred form of which isshown in the accompanying drawings, in which:

Figure 1 is a schematic view ofan open hearth furnace'e'quipped with animproved fuel atomizing apparatus embodying features of the presentinvention;

Figure 2 is a top plan viewwith parts broken away of a preferredconstruction of heat exchanger used in the apparatus shown in Figure 1;

Figures 3 and 4 are vertical sectional views of the heat exchanger takenrespectively on lines III-III and IV-IV of Figure 2;

Figure 5 is an enlarged vertical sectional view of the heat exchangershowing the wall construction;

Figure 6 is a side elevational view with parts broken away of apreferred construction of a multiple diaphragm by-pass valve used in theapparatus shown in Figure 1; and

Figure 7 is an exploded sectional view of the operating mechanism of thevalve shown in Figure 6.

Referring more in detail to the drawings:

In Figure 1 there is shown schematically an open hearth furnace I0,which is of the reversing type and has two selectively operable liquidfuel burners I 2 and I3 at opposite ends. The furnace is reversedperiodically and thus is fired alternately from these two burners, asknown in the art. There is'shown at I4 an air compressor which directscompressed air through a line I5 to a receiving tank l6. From the tankthe air passes via a line I! into a heat exchanger, where the air isheated to a temperature preferably between 600 and 800 F., commonlybeing maintained at 700 F., although these temperatures are not criticalas long as the temperature is maintained constant or nearly so. Line I!preferably has a pressure regulator l 9 and a by-pass valve for saidregulator. The pressure commonly is maintained between 75 and 125 poundsper square inch, although thesevalues too are not necessarily critical.The furnace, burners, air compressor, receiving tank, and pressureregulator may be of any standard construction; hence no more detaileddescription is deemed necessary. The preferred construction of heatexchanger is described more fully hereinafter.

A line 2| extends from the heat exchanger and branches into lines 22 and23 which extend respectively to burners l2 and I3. These lines containnormally closed, pneumatically operated diaphragm type valves 24 and 25respectively for controlling flow of air to the burners. Inasmuch asthese valves may be of any standard construction and per se are not partof the present invention, no more detailed description is deemednecessary. When the furnace is fired from either burner, the appropriatevalve is opened and directs air to that burner to act as the fuelatomizing fluid.

The apparatus comprises a by-pass line 26 which discharges from pipe 2|into the atmosphere and which contains a valve 21. This valve is of thenormally open, pneumatically operated double diaphragm type and is morefully described hereinafter. The apparatus comprises valve operatingmechanism which automatically opens valve 21 unless either valve 24 or25 is open, in which case it automatically closes valve 21. Thus the aircontinues to circulate through the heat exchanger when valves 24 and 25are both closed as during changeovers in firing the furnace from one setof burners to the other, as is done periodically in operation of thefurnace. Such circulation is needed to prevent overheating of the heatexchanger, since the temperature of air emerging from the heat exchangeris close to the maximum temperature which the heat exchanger canwithstand. Also if the heat exchanger is overheated, there is subsequentdifficulty in adjusting the air temperature to the desired constant.

The valve operating mechanism includes a control air line 28 which isconnected with line I! and thus receives compressed air from tank [6.Line 28 preferably contains a filter 29 and a pressure reducing valve30, which both may be of any standard construction. Line 28 extends to afour-way control valve 3|, to which are also connected an exhaust line32 and two lines 33 and 34 that extend to valves 24 and 25 respectivelyfor operating these valves. Valve 3| has settings to connect line 28with either line 33 or 34 and at the same time connect the other ofthese lines with exhaust line 32. Inasmuch as valves having suchsettings are known and per se are not part of the present invention, nomore detailed description is deemed necessary. Whenever the controlvalve admits air to line 33 or 34, valve 24 or 25 opens and air flowsthrough that valve from the heat exchanger to one of the burners.

Air lines 35 and 36 extend from air lines 33 and 34 respectively to theby-pass valve 21. Whenever control valve 3| is actuated to relieve thepressure on the diaphragm of either of the normally closed valves 24 or25 and thus close this valve, it also relieves the pressure thatmaintains the normally open by-pass valve closed. The bypass valvethereupon opens and maintains air circulation through the heat exchangervia bypass line 26 and thus prevents overheating of the heat exchanger.The by-pass valve remains open until pressure is applied to thediaphragm of the other valve 24 or 25 to open this valve. At the sametime pressure is applied automatically to the by-pass valve via line 35or 36 and thus this valve closes, and circulation is resumed to one ofthe burners.

A preferred construction of heat exchanger I8 is shown in detail inFigures 2 to 5. The heat exchanger comprises an enclosure whose wallsare formed of a heat insulation lining 31 supported by longitudinallyextending channel-- shaped casing members 38. Pairs of end plates 39 areinterposed between successive tiers of insulating material and casings(Figure 5). A spacer 40 and a horizontal bafiie 4| are interposedbetween each pair of end plates 39. The baffles are supported cantileverfashion from the end plates and thus are free to expand and contract.The bafiles extend alternately from opposite sides into the interior ofthe heatexchanger as best shown in Figure 3 and define a sinuous coursefor circulating waste products of combustion from the furnace from whichthe heat is derived.

A fan 42 draws a portion of the product of combustion from furnace intothe lower portion of heat exchanger |8 through an inlet 43. Theseproducts of combustion pass through the heat exchanger in the coursedefined by baffles 4| and are expelled at the top through an outlet 44into a stack 45 (Figure 1). The portion of such products which passthrough the heat exchanger is governed by a damper 46 preferably locatedin outlet 44.

The compressed air is maintained at a substantially constanttemperature. which may be controlled by regulating damper 46. Line 2|contains a temperature indicating device 41 and line I! contains a flowindicating device 48. Damper 46 is regulated in accordance with readingson these indicating devices to maintain a flow of products of combustionthrough the heat exchanger sufficient to heat the air to just thedesired temperature. Although the damper may be regulated manually, theapparatus preferably includes metering controls, connected to thetemperature and flow indicating devices 41 and 48 but not shown, forregulating the damper automatically. Inasmuch as such controls are knownand do not per se form a part of the present invention, no more detaileddescription is deemed necessary.

The heat exchanger has a pair of manifolds 49 and 59, each of which isdivided by partitions and into a plurality of superposed compartments(Figure 4). The compartments on opposite manifolds are connected byU-shaped tubes 52, which extend between baffles 4| into the path ofcirculation of the products of combustion. Unheated compressed air isintroduced from line I! to the top chamber of manifold 49, whence itpasses through tubes 52 to the top chamber of manifold 50. Such airthenreturns to the second chamber of manifold 49 via the next set of tubes52. Air circulation between the manifolds continues through the entireheight of the manifolds and the heated air finally discharges from thebottom chamber of manifold 49 into line 2|, from which it ma be directedto either set of burners as already explained.

Figures 6 and 7 show a preferred construction of by-pass valve 21. Saidvalve includes the usual body, stem and closures, which are not shown indetail, since they may be of any standard construction. The operatingmechanism for this valve includes a pair of superposed flexiblediaphragms 53 and 54 housed within the usual pressure chamber 55. Aspring 56 normally urges the diaphragms to a retracted position againstthe back wall of the chamber and normally maintains the valve open. Airmay be admitted to the spacebehind diaphragm 53 to close the valve, orair may be admitted to the space between the two diaphragms also toclose the valve. The first of these spaces is connected to line 36 by aconnection 51 in the back wall of the chamber. The second of thesespaces is connected to line 35 by a connection 58 situated in a spacerring 59 between the two diaphragms. The first space preferably hasfillers 60 and the second fillers 6| to separate the diaphragms slightlyfrom the end wall and from each other when either is retracted. Thus itis seen that the by-pass valve is closed whenever air i admitted behindeither diaphragm on closing of either valve 24 or 25.

While the valve just described is particularly suited to use in thepresent installation, similarly constructed valves may be employed inother installations where it is desired to operate a valve from any oneof a multiple of sources. Such valves may be either of the normally openttype, as illustrated, or of the normally closed From the foregoingdescription, it is seen that I have provided an efficient apparatus foratomizing fuel to either burner or set of burners utilizing compressedair as the atomizing fluid. The air iscontinuously heated by heatderived from waste products ,of combustion and circulation of air isautomatically(maintained at all times ineluding during changeoverperiods. Thus I have provided a system inyvhich there is no likelihoodof parts being overheated by failure to maintain air circulation.

The apparatus forsupplying compressed air to the burners and theatomizing method are not claimed in the present application for thereason that they form the subject matter of a continuation-in-partapplication Serial No. 148,619, filed March 9, 1950. The doublediaphragm valve is not claimed in the present application for the reasonthat it forms the subject matter of a divisional application Serial No.160,067, filed May 4, 1950.

While I have shown and described only a single embodiment of theinvention, it is apparent that modifications may arise. wish to belimited to the disclosure set forth but only by the scope of theappended claim.

I claim:

A heat exchanger comprising a base, a pair of side walls, a pair of endwalls and a top wall defining a heating chamber above said base, a pairof parallel vertically disposed manifolds fixed to one of said sidewalls, horizontal partitions in said manifolds dividing each of theminto superposed compartments with the partitions in one manifold beingstaggered with respect to those in the other manifold, a plurality ofintegral horizontal U-shaped tubes connecting adjacent compartments onopposite manifolds and extending back into the heating chamber, a

Therefore, I do not Number 5 pipe connected to an end compartment of oneof said manifolds for admitting gases to be heated, said manifoldcompartments and said tubes defining a continuous path through the heatexchanger for such gases, a pipe connected to a compartment at theopposite end of one of said manifolds for discharging heated gases,horizontal baffles extending from said end walls between said tubes withsuccessive batiies extending from opposite end walls and thus defining asinuous course, means for admitting hot gases to one end of this sinuouscourse for heating the tubes containing the first mentioned gases, andmeans for discharging the second mentioned gases from the other end ofsaid sinuous course.

JAMES L. HAR'INEY.

REFERENCES CE'EED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Re. 16,878 Leach Feb. 14, 1928 NumberNumber 6 Name Date Pollock Mar. 7, 1865 Fulton Nov. 22, 1906 JohnsonJan. 26, 1926 Jones et a1. Mar. 30, 1926 Kling Nov. 1, 1927 De FiorezJune 11, 1929 Primrose May 13, 1930 Trent June 24, 1930 Jacobsen Dec. 2,1930 Darrah Apr. 4, 1931 Gebhardt Jan. 19, 1932 Isley et a1. Mar. 7,1933 Schack Nov. 1, 1938 Kneass July 8, 1911 FOREIGN PATENTS CountryDate Great Britain 1872 Great- Britain 1992

